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Starter solenoid?

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Starter solenoid?
#1
sethmasia Avatar
sethmasia Seth Masia
Paonia, CO, USA   USA
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1974 MG MGB MkII
I bought a Chinese-built starter motor back in August or September and it worked fine. Then last week it didn't. Not a click. The relay I put in the starter circuit is good, as is all the wiring, battery (12.9v) and its cabling. Everything in the car works except the starter.

Took it out and can't get continuity across the solenoid poles, nor a resistance read-out. On a similar 10-year-old solenoid on one of my Guzzis, resistance across the poles is about 12 or 15 ohms. I'm assuming this means the new solenoid is dead. Second or third opinions?


Retired ski bum, maintaining a fleet of old motorbikes in the mountains of Colorado. In the barn: '70 TR6R, '74 TA125, '74 Guzzi 850T, '74 MGB, '89 Guzzi Mille, '99 F650, '13 XT250.

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Re: Starter solenoid?
#2
dickmoritz Avatar
dickmoritz Platinum Member Dick Moritz
Philly 'burbs, PA, USA   USA
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Disconnect the white/brown wire from the starter relay and touch it to the bottom fuse with gearstick in neutral. Does the starter turn? If not, use a little jumper wire, disconnect the white/brown wire from the starter solenoid and jump that terminal of the solenoid to the bottom fuse. Starter turn? Confirm 12+ volts at the large terminal of the solenoid where the B+ cable from the battery connects. Jump from this terminal to the spade on the solenoid. Starter turn? If not, use a screwdriver and jump across the two large terminals on the solenoid. Starter turn? If yes, solenoid is bad. If no, starter itself is bad...

Dick


Errabundi Saepe, Semper Certi
(Often wrong, but always certain)

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Re: Starter solenoid?
#3
sethmasia Avatar
sethmasia Seth Masia
Paonia, CO, USA   USA
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1974 MG MGB MkII
Thanks, Dick. I pulled the starter motor out and tested on the bench with a tractor battery and jumper cables. It works fine. So I'm back under the car looking at the heavy cables again, trying to find some resistance hidden under the road mung.


Retired ski bum, maintaining a fleet of old motorbikes in the mountains of Colorado. In the barn: '70 TR6R, '74 TA125, '74 Guzzi 850T, '74 MGB, '89 Guzzi Mille, '99 F650, '13 XT250.

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Re: Starter solenoid?
#4
jjonns74 Avatar
jjonns74 Gold Member John Dailey
Indianapolis, IN, USA   USA
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1974 MG MGB "Athena"
1974 MG MGB "Apollo"
Seth,

When I bench test my Starter Motor, I connect it as if it were in place on the car:

1. Jump Battery Ground to the Starter Motor Case = nothing happens
2. Jump Battery Positive to the Starter Solenoid "Power Stud" (larger Brass stud) = still nothing
3. Momentarily touch a jumper between the Power Stud and larger spade terminal of Starter Solenoid (simulating W/n wire from Starter Relay) = Solenoid engages & Starter Motor spins.

(You can also perform the above while Starter Motor is Installed - no jumper to case is required, as Starter Motor gets Ground from the engine block)
If no Joy, connect a jumper from Ground to Starter Motor case......

Confirm all wire connections to Power Stud are Clean & Tight
Confirm W/n wire from Starter Relay is on the larger spade terminal
Confirm braided Grounding Strap from Block to Driver's side motor mount is Clean/Tight.


JohnD

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Re: Starter solenoid?
#5
Drewski Avatar
Drewski Silver Member William Estaver
SUMMERVILLE, SC, USA   USA
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1973 MG Midget MkIII "Maggie"
In reply to # 4791602 by sethmasia Took it out and can't get continuity across the solenoid poles, nor a resistance read-out. On a similar 10-year-old solenoid on one of my Guzzis, resistance across the poles is about 12 or 15 ohms. I'm assuming this means the new solenoid is dead. Second or third opinions?

Yes, 12 to 15 sounds reasonable for the old solenoid as you are reading the windings of the solenoid coil. No 'click' and no continuity indicates 'open' windings, and failed new solenoid.



Edited 2 time(s). Last edit at 2024-05-02 07:01 AM by Drewski.

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Re: Starter solenoid?
#6
sethmasia Avatar
sethmasia Seth Masia
Paonia, CO, USA   USA
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1974 MG MGB MkII
Once the starter motor worked on the bench, I took the starter wiring circuit apart, from the battery to the fuse block. Cleaned all connections with DeOxit and a small file, buttoned it all back up and away we went. Just an accumulation of small voltage-robbing corrosion films, I guess. Cost nothing but about three hours of labor, and I give myself a generous discount.


Retired ski bum, maintaining a fleet of old motorbikes in the mountains of Colorado. In the barn: '70 TR6R, '74 TA125, '74 Guzzi 850T, '74 MGB, '89 Guzzi Mille, '99 F650, '13 XT250.

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